The present invention relates to a vehicle door latch device, and more particularly, to a vehicle door latch device with a double action mechanism.
German Patent DE 4,313,248 C2 discloses a double action mechanism (hereafter, referred to as a DA mechanism) provided in a door latch device for the purpose of improving the performance of crime prevention of the door latch device. The DA mechanism can be called an improved mechanism of a previously well known one-motion door opening mechanism. The conventional one-motion mechanism is approximately simultaneously capable of restoring the latch device from a locked state to an unlocked state and opening the door, when an inside open handle of the door is operated in a case where the door latch device is in the locked state.
On the contrary, the DA mechanism merely restores the latch device from the locked state to the unlocked state without opening the door, when the door-opening operation of the inside open handle is performed in the locked state. The DA mechanism opens the door in accordance with the door-opening actuation of the inside open handle only when the latch device is in the unlocked state. Accordingly, in order to open the locked door having a latch device with a DA mechanism by the inside open handle, both a first door-opening actuation of the inside open handle for restoring the latch device to the unlocked state from the locked state and a second door-opening actuation of the inside handle for releasing the latch device are necessary. Thus, the DA mechanism requires the double action of the inside open handle when opening the door, so that it can improve the performance of crime prevention of the door latch device.
In addition, in a door equipped with the latch device with the DA mechanism, an inside lock button which is provided on an inside surface of the door may be arranged such that it can be used only when switching the latch device from the unlocked state to the locked state. In other words, in some cases, the inside lock button has no function of switching the latch device from the locked state to the unlocked state. In such a case, the unlocking of the latch device is performed by the first door-opening actuation of the inside open handle. By removing the function of the unlocking operation from the inside lock button, the performance of crime prevention of the door can furthermore be improved. In order to remove the function of the unlocking operation from the inside lock button, in the prior art, the inside lock button in the locked position is hidden inside the fancy board or trim board of the door, so that the inside lock button cannot be picked by fingers.
The inside lock button in the locked position has a high performance of crime prevention against an illegal access from the outside since it is hidden in the fancy board, but the performance of crime prevention of the connecting portion between the inside lock button and the latch device provided in the inside space of the door remains as it has been in the prior art.
Accordingly, it is an object of the present invention to provide a latch device with a DA mechanism in which the performance of crime prevention of the connecting portion between the inside lock button and the lock lever of the latch device is improved.
In order to attain this object, in the present invention, an antitheft mechanism is provided between the inside lock button and the lock lever, which does not transmit the unlocking movement of the inside lock button to the lock lever.